Abstract

Microwave absorbing coatings composed of Co-Ferrite particles and carbonyl iron particles (CIP) as absorbent and aliphatic polyurethane resin as matrix were fabricated, and their electromagnetic and microwave absorbing properties could be tuned by changing the weight fraction of Co-ferrite at 4–18 GHz. The result of reflectivity indicates that the coating with Co-ferrite particles have excellent absorption in the range of 12 GHz–18 GHz with reflection loss below -10 dB. The absorption with carbonyl iron particles is less than -8 dB in the range of 4 GH–8 GHz. The hybrid of two particles was used to fabricate the coating in order to broadening the effective bandwidths. The reflectivity results demonstrated that the maximum absorption of the coating with hybrid particles is less than that containing only one kind particle. But the effective bandwidths (< -8 dB) increases to 13 GHz. This research work conludes that having both Co-Ferrite particles and carbonyl iron particles as absorbent is an effective way to broaden the bandwidths of absorption.

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